Swing arm for holding a dressing device

ABSTRACT

A swing arm for holding a dressing device is adapted for mounting on a column or base portion of a machine tool. The swinging end of the arm is disposed to hold a threaded dressing member while the arm is swung in an arc around a pivot shaft. The pivot shaft retains a pivot joint which includes a roller thrust bearing disposed between the fixed and the movable member with a spring-type washer urging the fixed and the rotatable member together in a determined frictional relationship. An O-ring is seated in a groove formed at the roller raceway so as to seal the thrust bearing as well as provide a dust seal and vibration dampener.

nited States Patent Swenson [4 1 June 13, 1972 [54] SWING ARM FORHOLDING A 3,233,949 2/1966 Rieman ..308/3 A DRESSING DEVICE 1,760,8005/1930 Wambsgans ..287/101 [72] inventor: Henry F. Swenson, 22 HolmehillLane, p H Whitehead Roseland, NJ. 07068 Attorney-Ralph R. Roberts [22]Filed. Dec. 16, 1970 ABSTRACT [21] 98654 A swing arm for holding adressing device is adapted for mounting on a column or base portion of amachine tool. The [52] U.S.Cl. ..l25/llR, 287/101 swinging end of thearm is disposed to hold a threaded 51 Im. c1 ..B24b 53/12 dressingmember while the arm is swung in an arc around a s8 1 Field of Search125/1 1, 1 1 A; 287/101; pivot Shaft The Pivot Shaft retains pivotioimwhich includes 30 3 A a roller thrust bearing disposed between the fixedand the movable member with a spring-type washer urging the fixed 56]References Cited and the rotatable member together in a determinedfrictional relationship. An O-ring is seated in a groove formed at theUNITED STATES PATENIS roller raceway so as to seal the thrust bearing aswell as provide a dust seal and vibration dampener. 1,266,707 5/1918Olson ..l25/ll A Spracklen ..287/101 6 Claim, 3 Drawing Figures IPATENTEDJUN 1 a man INVENT OR. HENRY E SWENSO/V BY 7 m AGENT SWING FORHOLDING A DRESSING DEVICE CROSS REFERENCE TO A RELATED APPLICATION Theswing arm of this application is shown as a preferred dressing toolholder used on and'with a center-hole grinder as shown and described inU.S. Pat. No. 3,548,545 which issued Dec. 22, 1970.

BACKGROUND OF THE INVENTION 1. Field of the Invention With reference tothe classification of art as established in the U.S. Patent Office thisinvention pertains to the class entitled, Stone Working," and moreparticularly to the subclass therein entitled grinding wheel dressing."

2 Description of the Prior Art Dressing devices for truing the face orfaces of grinding wheels usually. require the movement of a dressingdevice such as a diamond dresser across the face of a grinding wheel. Inorder that this dressing device be maintained in a true predeterminedpl'ane providing thedesired facing action, the movement of the movablearm must be precisely controlled. In the swing arm shown in thepreferred embodiment a springloaded pivot joint permits the dressingdevice to be selectively moved in a precise and prescribed are aroundthe pivot joint in a vibration dampened manner. An example of a swingingarm device is seen in U.S. Pat. No. Re. 26,920 which issued June 23,1970 to Parapetti. In this patent and others showing like devices thereis provided elaborate arm construction disposed to provide movementcontrol means which attempt to prevent unwanted and excessive vibrationof the dressing medium when and as it is moved over the face of agrinding wheel to effect dressing of said wheel to a determined facedcondition. In the dressing device shown in the .Parapetti patent and inmany similar devices the arm construction is extremely elaborate andexpensive and often does not provide the dampening effect necessary toprovide a true dressing or shaping of the grinding wheel. I I

In the present invention there is provided a simple swing arm oftwo-piece construction wherein a novel pivoted assembly providesa simplejoint of substantial strength and having a low friction. The pivot jointadditionally provides a selective, dampening action which is provided byan adjustably tightened cup-shaped spring washer which permits themovable arm to be swung while being restrained by a desired frictionalrestriction.

SUMMARY OF THE INVENTION swing action of the movable arm.

It is a further object of this invention to provide, and it doesprovide, a swing arm for holding a dressing device wherein the fixed armis attachable in an adjustable manner to a portion of a machine tool andin which the swinging arm portion is rotatably carried by ananti-frictional pivot joint, said swing arm having a threaded apertureat its outer end adapted to receive and adjustably retain a dressingholder having a threaded outer body.

The swing arm of this invention includes a support member which isremovably mounted to the machine tool. A swing member has its outer endprovided with a threaded aperture disposed to receive and retain agrinding wheel dressing means such as a diamond dressing point. Thepivot joint between the support and swing member provides ananti-friction arrangement in which a roller thrust bearing is mountedbetween the members and sealed from grit and dust by means of an O-ring.The head of the pivot pin is retained by a ball bearing while the otherend of the pivot pin and the whole joint is maintained in a determinedtensioned and frictional restraint by a cup-shaped spring washer whichis adjustably tightened to provide the desired frictional resistanceagainst vibration and rotation.

In addition to the above summary the following disclosure is detailed toinsure adequacy and aid in understanding of the invention. Thisdisclosure, however, is not intended to prejudice that purpose of apatent which is to cover each new inventive concept therein no matterhow it may later be disguised by variations in form or additions offurther improvements. For this reason there has been chosen a specificembodiment of the swing arm as adopted for use in grinding wheeldressing and showing a preferred means for mounting the arm to the baseor other fixed portion of a machine tool.

This specific embodiment has been chosen for the purposes ofillustration and description as shown in the accompanying drawingwherein:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 represents a sectional side viewshowing the preferred construction and assembly of the swing arm of thisinvention;

FIG. 2 represents a plan view of the arm of FIG. 1, the view taken onthe line 22 of FIG. 1, and

FIG. 3 represents, in an enlarged sectional view, a fragmentary portionof the roller thrust bearing and the means for mounting an O-ring toprovide the shielding for the thrust bearing necessary to prevent thepenetration of dirt, dust or other contaminants into the rollers of thethrust bearing.

In the following description and in the claims various details will beidentified by specific names for convenience; these names, however, areintended to be generic in their application. Corresponding referencecharacters refer to like members throughout the several figures of thedrawing.

The drawing accompanying, and forming part of, this specificationdiscloses certain details of construction for the purpose of explanationof the broader aspects of the invention, but it should be understoodthat structural details may be modified in various respects withoutdeparture from the concept and principles of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in particular toFIGS. 1 through 3, it is to be noted that a fixed member 10 is formedwith an elongated slot 12 extending longitudinally through a substantialportion of the member. This slot is shouldered to receive and retain thehead 14 of a socket head cap screw 16 seen in phantom outline in FIG. 1.This arm 10 has its right end reduced in thickness to provide an upperface portion 18 of a flat determined extent. In the middle of this faceportion and at right angles thereto is formed an aperture 20 ofdetermined size which is disposed to receive the outer diameter of theshank of a headed pivot pin 22.

A swinging arm member 30 is shown partly in section in FIG. 1 andincludes a threaded aperture 32 formed through the right or distal endof the swing member 30. The left or pivoted end of this member isreduced slightly in thickness to provide a flat and parallel surface 34adapted to support one of the race members of a roller thrust bearing38. This thrust bearing is of a conventional construction and has twofacing race members which are identified as 40 and 42. These racemembers are usually hardened and ground steel designed to support thethrust or load of a plurality of rollers 44 in a customary manner. Theserollers are shown as carried in a cage 46 which is normally providedwith a roller thrust bearing. A rubber O-ring 50 is sized to seat inchamfered shoulders 52 and 54 which are formed on the outer facing edgesof members 40 and 42 so as to provide a smooth retaining seat for theO-ring when the bearing has been mounted in its usual rotatingcondition. In its assembled condition as seen in FIG. 3, the O-RING 50is in a slightly stretched condition when it is 54. The snug fit of theO-ring provides a dust and dirt shield and at the same time it providesa small degree of restriction to the relative movement of race members40 and 42 to one another.

The chamfered shoulders 52 and 54 are specially formed on members 40 and42 so that in its assembled condition a determined groove is provided.The groove shoulders are preferably quite smooth so that the O-ring mayslide on these surfaces without attrition of the O-ring and to reducethe ability of dust, dirt and wet slurry to enter the bearing.

Arm 30 has an aperture 60 formed therein which is sized to provide arotative guide and retention of the shank of pivot pin 22. A shoulderedrecess 62 is formed on the underside of arm 30 and is made concentricwith aperture 60. This recess receives and retains the outer race of aball bearing 64. This bearing 64 is contemplated to be a combinationradial and thrust bearing of conventional configuration. The inner raceof the bearing 64 receives the shank of the pivot pin 22 and alsoaccepts and retains the thrust load exerted by the head of the pivotpin.

Pivot pin 22 is headed at one end which as seen in FIG. 1 is the lowerend. In the preferred embodiment, a threaded aperture 66-is formedaxially through pin 22 and may have threads per inch for receiving aone-quarter inch screw. A cup-spring washer 70 has a determined outerdiameter and an inner diameter whose aperture is adapted to receive thehead 72 of an oval-headed screw 74 and to seat this head in the inneraperture of the washer 70. The threaded shank of the screw 74 is mountedin and retained in the threaded aperture 66 in the pivot shaft 22. A setscrew 76 is shown as also mounted in the threaded hole 66 and isaccessible through the head end of the pivot shaft 22 so as to berotatably tightened to lock the screw 74 in its adjusted position.

USE AND OPERATION OF THE SWING ARM Preferably member 10 is brought to asupport member 80 as seen in phantom outline in FIG. 1. This supportmember is provided with a taped or threaded hole 82 adapted to receivethe threaded end of cap screw 16. The member 10 when screw 16 istightened is brought into a determined clamped or retained relationshipwith body 80. A wedge member 84 may be mounted in a groove and hole inmember 80, or any other suitable type of adjusting support block orwedge member may be provided so that member 10 may be slid back andforth and tilted to provide a desired angular relationship of member 10to the block. This also determines the angular relationship of threadedhole 32 to the face of the grinding wheel to be dressed. This grindingwheel being of any conventional configuration and mounting has not beenshown. With member 10 in.a locked condition in a desirable angle to andon the body member 80, the arm 30 may be now moved around the pivot pin22 by manipulation of the outer end of the arm 30. The screw 72 isrotated in or out to provide a determined tension or load on the thrustbearing 38 and the ball bearing 64. The tension or load is increased inresponse to the degree of flatening of the cup-shaped washer 70. Agrinding wheel dressing device is contemplated as being carried by athreaded shank 86 shown in phantom outline in FIG. 1. The dressingdevice is adjusted as it is rotated in or out in the threaded aperture32 and is moved forwardly or backwardly the amount necessary or desiredto bring the dressing end of the member in way of the face of thegrinding wheel to be dressed.

The roller bearing 38 provides a smooth anti-friction support of member30 by member 10. The bearing 64 insures that the member 30 as it isrotated around the head of the pinion member 22 moves with an equalamount of restraint. As the thrust load developed by the tightening ofspring 70 places a like load upon the bearing 64 it is desirable thatthe bearing 64 be a ball bearing having properties adapted to accept andmaintain at all angles or rotation the determined amount of thrustprovided by the spring 70. The screw 72 is adjusted to provide thedesired degree of bias or load on the bearings 38 and 64 so that as thearm 30 is moved to a determined dressing position it will stay at thisposition while the dressing device carried by shank 86 is rotatedforward and back to the desired dressing condition whereupon the arm 30is swung in an arc to dress the face of the grinding wheel in thedesired manner.

The swing arm of this invention provides'a simple means of providing ananti-friction joint having a high thrust capacity as provided by meansof a pre-loaded roller thrust bearing. The rollers and facing raceway ofthis bearing are protected from contamination by grit and dust by meansof an O-ring snugly mounted in the groove provided by the chamferedshoulders 52 and 54 formed in the facing outer edges 40 and 42 of thebearing 38. The spring provides a dampening effect to the arm to reduceif not eliminate the vibrations which develop during the movement of thedressing device over the face of the grinding wheel. The O-ring when itsstretched condition also acts as a partial dampener as well as providinga drag or brake to the rotative movement of arm 30 around the pivot pin22.

Whether the member 10 is mounted on a base or a column of a machine toolit is desirable that the arm be rigidly attached to permit only aminimum vibration. Adjustment for the angle of dress of the face of thegrinding wheel is provided by changing the angle of mounting of member10. Whether by means of a wedge member 82 or by some other anglesupport, the arm in its retained condition is mounted so that the axisof the pivot pin is at right angles to the line of dress of the grindingwheel. The dressing device may be either a diamond, a carborundum (TM,The Carborundum Company, Niagara Falls, New York) stick or otherdressing means carried in a holder which is adjustably carried in arm 30so as to be precisely moved to the desired dressing condition.

It is to be noted that for the cup-shaped spring 70 a resilient membersuch as a rubber washer may be used. A flat metal washer under the headof the screw of course would be used to transmit the effectivecompressive force to the rubber washer. Instead of a roller bearing 64other bearings such as porous bronze could be used. Instead of screw 74in threaded aperture 66 the pivot pin 22 may have an exterior threadedend and a nut mounted thereon. The bearing 64 could be mounted in arm 10and pivot pin 22 reversed in its mounted arrangement with washer 70 andscrew 74 disposed on the bottom of the assembly of FIG. 1.

Terms such as left, right, up, down," bottom, top," front, back, in, outand the like are applicable to the embodiment shown and described inconjunction with the drawing. These terms as used are merely for thepurpose of description and do not necessarily apply to the position inwhich the swing arm may be constructed or used.

While a particular embodiment of the swing arm has been shown anddescribed it is to be understood the invention is not limited theretoand protection is sought to the broadest extent the prior art allows.

What is claimed is:

l. A swing arm assembly for holding a dressing device for grindingwheels and the like, said swing arm assembly including: (a) a fixedsupport member adapted for removable attachment to a base, column andlike fixed portions of a machine tool carrying the grinding wheel to bedressed, said fixed member having one end formed to provide a determinedflat surface and with a first aperture formed through this flat surfaceportion, this first aperture having its axis normal to the plane of theflat surface; (b) a swing member pivotally attached to and supported byone end of the fixed support member, said swing member having a flatsurface portion formed at its pivoted end and with a second apertureformed through this flat surface, said second aperture having its axisnormal to the plane of said flat surface; (c) a pivot pin providing thepivoted support of the swing arm on the fixed support member, said pivotpin mounted in and through said first and second apertures; (d) rollerthrust bearing having opposed raceway members and mounted on the pivotpin and between the opposed flat faces of the fixed and swing members;(e) a resilient ring seal in a slightly stretched condition engaged in agroove formed by a chamfer on facing outer edges of the opposed racewaymembers of the thrust bearing, said seal preventing dust, dirt and thelike from entering the bearing while also providing a brake action tothe relative rotative movement of the thrust bearing raceways; (f)biasing means for urging the fixed and swing members toward each otherwhile also providing a vibration dampner and pre-load to the thrustbearing, and (g) holding means provided on the distal end of theswinging arm for holding a dressing device for a grinding wheel, theholding means in combination with the dressing device adapted to beadjustably moved to a selected position in a plane parallel to the planeof the movement of the swing arm around the pivot pin.

2. A swing arm assembly for holding a dressing device as in claim 1 inwhich the pivot pin is a headed pin having thread means provided atleast at the opposite shank end thereof and the biased means is a springmember which is adjustably compressed by a threaded member retained bythe thread means of the pivot pin.

3. A swing arm assembly for holding a dressing device as in claim 2 inwhich the thread means of the pivot pin is a threaded aperture and thethreaded member is a headed screw carried therein.

4. A swing arm assembly for holding a dressing device as in claim 3 inwhich there is provided a set screw also carried in the other end of thethreaded aperture of the pivot pin, said set screw disposed to betightened to retain the headed screw in its adjusted condition.

5. A swing arm assembly for holding a dressing device as in claim 2 inwhich the member against which the head of the pivot pin is drawn isprovided with an anti-friction bearing disposed to engage the head ofthe pivot pin so that any relative motion of the member and the pivotpin is made with said anti-friction bearing interposed between the headand member.

6. A swing arm assembly for holding a dressing device as in claim 5 inwhich the anti-friction bearing engaging the pivot pin head is a ballbearing having both radial and thrust capacity.

1. A swing arm assembly for holding a dressing device for grindingwheels and the like, said swing arm assembly including: (a) a fixedsupport member adapted for removable attachment to a base, column andlike fixed portions of a machine tool carrying the grinding wheel to bedressed, said fixed member having one end formed to provide a determinedflat surface and with a first aperture formed through this flat surfaceportion, this first aperture having its axis normal to the plane of theflat surface; (b) a swing member pivotally attached to and supported byone end of the fixed support member, said swing member having a flatsurface portion formed at its pivoted end and with a second apertureformed through this flat surface, said second aperture having its axisnormal to the plane of said flat surface; (c) a pivot pin providing thepivoted support of the swing arm on the fixed support member, said pivotpin mounted in and through said first and second apertures; (d) rollerthrust bearing having opposed raceway members and mounted on the pivotpin and between the opposed flat faces of the fixed and swing members;(e) a resilient ring seal in a slightly stretched condition engaged in agroove formed by a chamfer on facing outer edges of the opposed racewaymembers of the thrust bearing, said seal preventing dust, dirt and thelike from entering the bearing while also providing a brake action tothe relative rotative movement of the thrust bearing raceways; (f)biasing means for urging the fixed and swing members toward each otherwhile also providing a vibration dampner and pre-load to the thrustbearing, and (g) holding means provided on the distal end of theswinging arm for holding a dressing device for a grinding wheel, theholding means in combination with the dressing device adapted to beadjustably moved to a selected position in a plane parallel to the planeof the movement of the swing arm around the pivot pin.
 2. A swing armassembly for holding a dressing device as in claim 1 in which the pivotpin is a headed pin having thread means provided at least at theopposite shank end thereof and the biased means is a spring member whichis adjustably compressed by a threaded member retained by the threadmeans of the pivot pin.
 3. A swing arm assembly for holding a dressingdevice as in claim 2 in which the thread means of the pivot pin is athreaded aperture and the threaded member is a headed screw carriedtherein.
 4. A swing arm assembly for holding a dressing device as inclaim 3 in which there is provided a set screw also carried in the otherend of the threaded aperture of the pivot pin, said set screw disposedto be tightened to retain the headed screw in its adjusted condition. 5.A swing arm assembly for holding a dressing device as in claim 2 inwhich the member against which the head of the pivot pin is drawn isprovided with an anti-friction bearing disposed to engage the head ofthe pivot pin so that any relative motion of the member and the pivotpin is made with said anti-friction bearing interposed between the headand member.
 6. A swing arm assembly for holding a dressing device as inclaim 5 in which the anti-friction bearing engaging the pivot pin headis a ball bearing having both radial and thrust capacity.